افزایش سن مدولاسیون مغناطیسی ترانس کرانیال هیپوکامپ پتانسیلهای برانگیخته را تحت تأثیر قرار می دهد

Transcranial magnetic stimulation (TMS) is being proposed as a method of choice for the treatment of clinical depression, yet its action in the brain is still not well understood. In previous studies we found that TMS has a long-term effect on reactivity of the hippocampus to perforant path stimulation. Since the efficacy of antidepressants is highly age-dependent, we studied possible age-related effects of TMS on hippocampal evoked responses. Young adult (3 months), aging (10 months) and aged (24–26 months) awake rats were subjected to daily TMS for one week, followed by measurements of several parameters of reactivity to perforant path stimulation in the anesthetized rat. TMS did not affect responses of the hippocampus to single perforant path stimulation, but reduced drastically paired-pulse and frequency dependent depression in the young and aging but not the old rats. Likewise, TMS increased LTP expression in the young but not the old rats, and reduced the efficacy of serotonin modulation of reactivity of the hippocampus, in the young but not the old rats. Thus, long term effects of chronic TMS on local GABAergic inhibition are highly age dependent.

Depression is a prominent psychiatric disorder in the elderly [7], [13], [21], [23] and [38]. Serotonin-specific reuptake inhibitors (SSRI) and tricyclic antidepressant (TCA) are in general less effective in treating depression in aged patients than in their younger counterparts [31]. In the elderly patient, the time required for the improvement of depressive symptoms with antidepressant therapy has been reported to be as long as 6–12 weeks [3] and [10]. This pattern of reduced therapeutic efficacy is characteristic of SSRI and TCA and involves an age-related decline in the serotonergic neuronal system [8] and [38]. Age-related alterations in the synthesis, release, and turnover of serotonin [16], [39] and [40] 5-HT receptor density [2], [11] and [30], density of the 5-HT transporter [1] and [42] as well as physiological sensitivity to serotonergic agonists [6], [26] and [27] have also been described.